Effect of aging on the prognostic significance of ambulatory systolic, diastolic, and pulse pressure in essential hypertension

Background-This study compared the relative prognostic significance of 24 hour intra-arterial ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP) parameters in middle-aged versus elderly hypertensives. Methods and Results-A total of 546 subjects aged < 60 years and 142 subjects aged greater than or equal to 60 years who had undergone baseline pretreatment 24-hour intra-arterial ambulatory blood pressure monitoring were followed for 9.2 +/- 4.1 years. Multivariate analysis showed that in younger subjects, 24-hour, daytime, and nighttime DBP, MAP, and SBP, when considered individually, were positively related to morbid events; DBP parameters provided the best predictive values. In the group greater than or equal to 60 years (elderly group), 24-hour, daytime, and nighttime PP and SBP were the most predictive parameters, whereas ambulatory DBP and MAP measurements failed to provide any prognostic value. When 24-hour values of SBP and DBP were jointly included in the baseline model, DBP (z=2.02, P=0.04) but not SBP (z= -0.43, P=0.67) was related to outcome in younger subjects, whereas in the elderly group, SBP (z=3.33, P=0.001) was positively and DBP (z= - 1.75, P=0.07) was negatively related to outcome. Clinic blood pressure measurements failed to provide any independent prognostic value in either age group. Conclusions-The relative prognostic significance of ambulatory blood pressure components depends on age; DBP parameters provided the best prognostic value in middle-aged individuals, whereas PP parameters were the most predictive in the elderly. This may reflect differing underlying hemodynamic mechanisms of hypertension in these age groups.